The present disclosure relates to proximity sensing techniques for mobile devices to sense proximity of the touchscreen display of the device to the user, and in particular, to sensing techniques based on sound rather than light.
Proximity sensing is an important feature for touchscreen based mobile devices to detect the close presence of a part of the body of the user to, in the case of a user face, switch off the touchscreen display to prevent false touch events during voice calls, or, in the case of a user hand, to switch on the touchscreen display to enable touch events during device operation. Current mobile devices use infrared (IR) sensors to perform proximity sensing, which require area(s) adjacent the touchscreen on the front of the device. With devices trending toward significantly less frontal area available for a bezel, loss of space for IR sensors will require an alternative proximity sensing technique.